1. Field of the Invention
The present invention relates to a reflection type liquid crystal display device, and in particular, to a reflection type liquid crystal display device that can be manufactured more easily than a conventional reflection type liquid crystal display device.
2. Description of the Related Art
In general, a liquid crystal display device is available in a transparent type device provided with backlighting and a reflection type device. A reflection type liquid crystal display device uses only external light such as sun light, illumination light and displays without backlighting, and is used mainly in a personal digital assistant required to be thin and lightweight.
FIG. 4 is a partial cross sectional view of one example of a conventional liquid crystal display device of reflection plate built-in type. The liquid crystal display device 1 of reflection plate built-in type generally comprises a pair of vertically-opposed glass substrates 2 and 3, a sealing member 4 sandwiched by the pair of glass substrates 2 and 3, and liquid crystal 5 sealed in a space surrounded by the sealing member 4 and the pair of glass substrates 2 and 3. On the obverse surface of the upper glass substrate 2, phase difference plates 6, 7 and a polarizing plate 8 are laminated from the bottom side. On the reverse surface of the upper glass substrate 2, a color filter 9, a flattening film 17, an electrode layer 10 made of ITO (indium tin oxide), an orientation film 31 are laminated. Further, on the obverse surface of the lower glass substrate 3, an organic film 12 having depressions and projections on the surface thereof, a metallic reflection film 13, a flattening film 14, an electrode layer 15 made of ITO, and an orientation film 16 are laminated in order.
FIG. 5 is a partial enlarged cross sectional view of the portion near the end of the metallic reflection film 13 of the liquid crystal display device 1 of reflection plate built-in type. In the drawing, it should be appreciated that the various elements have not been drawn to exact scale and that some dimensions have been emphasized so that the invention disclosed can be clearly understood. The thickness of the lower glass substrate is about 0.7 mm, the maximum thickness of the organic film 12 is about 4 .mu.m, the thickness of the metallic reflection film 13 is about 1000 .ANG., the maximum thickness of the flattening film 14 is about 5 .mu.m, and the thickness of the electrode layer 15 is about 2000 .ANG.. Further, the height of the depression and projection on the surface of the organic film 12 is about 1 to 2 .mu.m.
When the depressions and projections are formed on the surface of the organic film 12 laminated on the lower glass substrate 3 by pressing a die to manufacture the reflection body, the shape of depression and projection tends to be disturbed at the end of the depressed and projected surface and an extremely pointed protrusion 12a, as shown in FIG. 5, might be formed. If the pointed protrusion 12a is formed, it is difficult to flatten the depressed and projected surface by the insulating flattening film 14 and hence the electrode layer 15 might be broken, or the metallic reflection film 13 and the electrode layer 15 might make a short circuit at the pointed protrusion 12a. In particular, in the electrode terminal forming region where the wiring lines of the electrode layer 15 are made dense because they are connected to a LSI or the like and where a wiring pattern is made complex because a circuit is formed, there is a strong possibility that the defective electrode layer 15 causes a serious problem in the liquid crystal display device 1 of reflection plate built-in type.
On the other hand, an alignment mark is formed on the glass substrate as a part used for aligning the glass substrates which are overlaid on each other or for printing the sealing member or the color filter on the substrate. FIG. 6 is a cross sectional view of one example of the alignment mark formed on the glass substrate. As shown in FIG. 6, the alignment mark 15a on the lower glass substrate 3 is formed by patterning ITO, which is the same layer as the electrode layer 15, on the peripheral portion of the lower glass substrate 3. In this respect, if the depressions and projections are formed on the entire surface of the lower glass substrate 3, it is difficult to recognize the alignment mark 15a and hence to manufacture the liquid crystal display device.